Field of the Invention
This disclosure relates generally to blood pump systems, and more particularly to blood pump systems and operation methods associated therewith.
Description of the Related Art
Generally, blood pump systems are employed in either of two circumstances. First, a blood pump may completely replace a human heart that is not functioning properly, or second, a blood pump may boost blood circulation in patients whose heart is still functioning although pumping at an inadequate rate.
For example, U.S. Pat. No. 6,183,412, which is commonly assigned and incorporated herein by reference in its entirety, discloses a ventricle assist device (VAD) commercially referred to as the “DeBakey VAD®.” The VAD® is a miniaturized continuous axial-flow pump designed to provide additional blood flow to patients who suffer from heart disease. The device is attached between the apex of the left ventricle and the aorta.
Many known blood pump systems typically are controlled in an open loop fashion where a predetermined speed is set and the flow rate varies according to the pressure differential across the pump. The pump itself may be controlled in a closed loop fashion, wherein the actual pump speed is fed back to a motor controller that compares the actual speed to the desired predetermined speed and adjusts the pump accordingly. Other pumps may be controlled in a closed loop fashion, in which the pump speed is varied according to a monitored parameter of the patient, such as the patient's pulse or blood flow rate.
Whether the pump is operated in a closed loop or open loop fashion, it is desirable to monitor several pump operating parameters, such as voltage level, current level, pump speed, flow rate, and the like. Adding additional measurement devices to the pump system, however, can complicate the system and add to the power requirements for the system.